Wellington, Sep 1 (TIWN) New Zealand Prime Minister Jacinda Ardern on Tuesday announced that the gunman, who killed 51 people at two mosques in Christchurch last year and was sentenced to life in prison without parole, has been designated as a terrorist entity.

"Designating the offender is an important demonstration of New Zealand's condemnation of terrorism and violent extremism in all forms," Ardern said in a statement.

A designation under New Zealand legislation freezes the assets of terrorist entities and makes it a criminal offence to participate in or support the activities of the designated terrorist entity, the prime minister said.

"This designation ensures the offender cannot be involved in the financing of terrorism in the future," Ardern said.

"We have an obligation to New Zealand and to the wider international community to prevent the financing of terrorist acts," she said.

There are currently 20 terrorist entities designated under New Zealand law, including this offender, the statement said.

Under Section 22 of the Terrorism Suppression Act 2002, the prime minister may designate individuals or groups as terrorist entities, on advice from officials.

Details of the designations process and the statements of case supporting designation of these entities can be found on the New Zealand Police website, it said.